Henna extract as a potential sacrificial agent in reducing surfactant adsorption onto quartz sand and kaolinite

Abstract

Surfactant flooding is one of enhanced oil recovery techniques to increase oil recovery. However, the main concern of this technique is the adsorption of surfactant onto reservoir rock which can reduce the effectiveness of the surfactant in reducing interfacial tension of oil and water. In this case, surfactant adsorption is normally reduced with the help of a sacrificial agent (SA). Studies have recently discovered the potential of plant extracts as an environmentally friendly and easily available alternative to chemical SAs. The main objective of this study is to evaluate the performance of henna extract as a SA in reducing surfactant adsorption. First, henna leaves were extracted and characterised to determine the functional groups responsible for adsorption. The ability of the henna extract to adsorb onto quartz sand and kaolinite was then analysed. Moreover, the adsorption limitation of the henna extract onto both quartz sand and kaolinite in different salinities, pH, and temperature was investigated. Finally, the performance of the surfactant adsorption onto quartz sand and kaolinite in the presence of the henna extract was evaluated. The results show that phenolic compounds are responsible for adsorption of the henna extract. Besides, twice the amount of henna extract was adsorbed onto kaolinite than quartz sand. Also, the henna extract managed to adsorb further when salinity was increased and pH was lowered. However, the adsorption of henna extract reduced with increasing temperature. The adsorption of henna extract is mainly through hydrogen bonding and electrostatic attractions while hydrophobic interactions play a minor role in the adsorption process. The henna extract reduced surfactant adsorption onto quartz sand and kaolinite by 46% and 55%, respectively, in 30,000 mg/L of NaCl. At pH 3, the surfactant adsorbed onto quartz sand and kaolinite was reduced by 32% and 39% respectively. Meanwhile, at 25oC, the surfactant adsorption onto quartz sand and kaolinite was reduced by 23% and 36%, respectively. This finding proves the profound reduction in surfactant adsorption with the addition of henna extract, suggesting the possibility of utilising the extract as a sacrificial agent to reduce surfactant adsorption. In conclusion, the adsorption behaviour of henna extract in different salinity, pH, and temperature was successfully demonstrated and the henna extract was found effective as a sacrificial agent in reducing surfactant adsorption.